Estimating community tobacco use by analysing wastewater

Ezine

Published: Sep 15, 2015

Author: Ryan De Vooght-Johnson

Channels: HPLC

Tracing trends in consumption

The chemical analysis of municipal sewage is becoming increasingly popular for following changes in community consumption. This method, also known as sewage epidemiology, relies on the detection of metabolites found in human urine and has traditionally been used to estimate the consumption of illicit drugs.

This direct measurement approach generally provides more accurate estimates of consumption than statistical tools like population surveys, medical records or drug production rates. It can also be carried out at regular intervals to reveal long-term trends in drug consumption, information that can subsequently be used to assess the effectiveness of intervention strategies.

Although estimating the prevalence of illegal drug use is important for governments, more commonly used legal substances are perhaps of greater concern. Tobacco smoking, for example, places a huge burden on healthcare systems and is responsible for the greatest number of preventable deaths. As a result, governments across the globe have introduced measures to reduce levels of smoking. Assessing tobacco consumption based on analysis of wastewater can help to measure the impact of these legislative changes.

Currently, wastewater analysis of tobacco consumption is based on nicotine (the major alkaloid and active compound in tobacco) and its urinary metabolite cotinine. This is inherently flawed, as nicotine is also found in replacement therapies, such as gums and patches, as well as in electronic cigarettes. Analysing nicotine is therefore not specific for smoking cigarettes.

However, there are other alkaloids present in dried tobacco that are not found in replacement therapies. In particular, anabasine and anatabine show promise as tobacco-specific biomarkers, and are in fact already used to detect non-adherence in patients on smoking cessation regimes. However, their potential for wastewater analysis is not yet known.

Addressing this knowledge gap, a recent study – conducted by researchers at the University of South Australia – assessed whether the two alkaloids could be used as biomarkers in wastewater. Nicotine and cotinine were also included in the study in order to distinguish between nicotine intake specifically from tobacco and overall nicotine intake.

Detecting tobacco-specific analytes in wastewater

The researchers applied solid-phase extraction (SPE) and liquid chromatography–mass spectrometry (LC-MS) techniques to detect the analytes in municipal wastewater. Liquid chromatography was optimised to separate nicotine and anabasine, which are close structural isomers. The methods were validated based on US Food and Drug Administration bioanalytical method validation guidelines.

All compounds were found to have adequate recovery, accuracy, precision and stability. Importantly, the researchers achieved chromatographic separation of the compounds. This was essential to differentiate between nicotine and anabasine, which share the same parent mass and several daughter transitions.

The methods were applied to wastewater samples collected from a treatment site in Adelaide. The samples were preserved using sodium metabisulphate and stored for up to a week before analysis. Filtration, SPE and LC-MS were carried out on the samples.

All four analytes were detected in all wastewater samples, at levels far above the method’s limit of quantification. The daily excreted mass load per 1000 people was calculated for each compound by multiplying the concentration of the analyte by the daily flow volume, and then dividing this figure by the service population. Daily flow volume and catchment population data were provided by SA Water, the operator of the sewer network.

Real-time monitoring of smoking patterns

This study shows that anabasine and anatabine are suitable biomarkers of tobacco use in wastewater. They are stable in wastewater (providing sufficient time for analysis), can be preserved effectively using a chemical agent and freezing, and have a low affinity for particulates in wastewater.

The SPE and LC-MS method used to detect anatabine and anabasine in wastewater samples demonstrated here could be used to monitor tobacco consumption within a community, with changes in the absolute amounts of markers in wastewater indicating changes in tobacco use over time. The researchers say this technique could be used to assess the efficacy of reduction strategies.

Once the urinary excretion rates of smoke anabasine and anatabine are better known, it will become possible to extend the existing back-calculation to use levels of these biomarkers to estimate the number of cigarettes smoked per 1000 people. This will represent a much more accurate method of assessing tobacco use than current calculations based on nicotine, which can also be consumed via replacement therapies, e-cigarettes and dietary sources.

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